Process for the preparation of imidazolones

Abstract

The present invention relates to a process for the preparation of a compound of general formula (I), ##STR1## wherein R 1 represents a hydrogen atom or an alkyl group of 1-6 carbon atoms, and their salts, wherein the compound of formula (II): ##STR2## is reacted with a compound of formula (III): ##STR3## wherein R represents an alkyl group of 1-4 carbon atoms and R 1 is the same as defined above, by heating their neutral pH mixtures at the boiling temperature of the mixture, and the resulting compound of general formula (IV): ##STR4## wherein R and R 1 are the same as defined above, is cyclized into the compound of general formula (I) by further elevating the temperature of the neutral mixture, and if desired, the compounds of general formula (I) are transformed into their salts, or the compounds of general formula (I) are liberated from their salts.

What is claimed is: 
     
       1. A process for the preparation of a compound of general formula (I): ##STR5## wherein R 1  represents a hydrogen atom or an alkyl group of 1-6 carbon atoms, and their salts, wherein the compound of formula (II): ##STR6## is reacted with a compound of formula (III): ##STR7## wherein R represents an alkyl group of 1-4 carbon atoms and R 1  is the same as defined above, by heating their neutral pH mixtures at the boiling temperature of the mixture, and the resulting compound of general formula (IV): ##STR8## wherein R and R 1  are the same as defined above, is cyclized into the compound of general formula (I) by further elevating the temperature of the neutral mixture, and if desired, the compounds of general formula (I) are transformed into their salts, or the compounds of general formula (I) are liberated from their salts. 
     
     
       2. The process as defined in claim 1, wherein the reaction of the compound of formula (II) with the compound of general formula (III), where R is a methyl group, and R 1  is n-butyl group, is carried out by heating at 70-80° C. under reflux conditions. 
     
     
       3. The process as defined in claim 1, wherein the resulting compound of general formula (I) is transformed in the reaction mixture into its hydrochloride salt and isolated in the form of this salt. 
     
     
       4. A compound of general formula (IV): ##STR9## wherein R is an alkyl group of 1-4 carbon atoms and R 1  is a hydrogen atom or an alkyl group of 1-6 carbon atoms. 
     
     
       5. N-(1-carboxamidocyclopentyl-1)-formimino ethyl ether. 
     
     
       6. N-(1-carboxamidocyclopentyl-1)-pentanimino methyl ether.